1. Field of the Invention
The present invention relates to a digital image processing apparatus and a method of operating the same, and more particularly, to a focusing apparatus and method which enables an image sensor to read only pixels within a preset region of an image, calculates a focus value using the read pixels, and applies the calculated focus value to the entire image.
2. Description of the Related Art
In general, digital image processing apparatuses convert an electrical image signal of an object into a digital signal using a sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS), and stores the digital signal using a compression/recovery unit or outputs the digital image using an output unit.
Such digital image processing apparatuses perform autofocusing to correctly focus an object. The autofocusing is performed by calculating a focus value using an edge, which is output after an image signal is processed by a sensor such as a CCD or a CMOS, for every picture, determining a moving direction and a moving distance of a focus lens on the basis of the calculated focus value, and moving the focus lens in the determined moving direction by the determined moving distance.
In an autofocus mode, the sensor such as a CCD or a CMOS, reads all pixels of the object at a rate of 30 frames per second (FPS). For example, when one frame comprises 256 pixels, a time taken to read one pixel at a rate of 30 FPS is 0.117 ms. Accordingly, a time taken to read all the 256 pixels is approximately 30 ms. In a high-speed autofocus mode, pixels of some lines are read and pixels of other lines are skipped in order to reduce a time taken to read the pixels. For example, when pixels of a first line are read and pixels of a third line are skipped, since only 64 pixels among 256 pixels are read, a time taken to read the 64 pixels is approximately 7.488 ms (133 FPS).
However, although pixels of some lines are read and pixels of other lines are skipped as described above, there are still a lot of pixels to be read by the sensor. Accordingly, conventional digital image processing apparatuses have limitations in increasing a focusing speed, and actually read unnecessary pixels as well.